The present invention relates to metal die casting machines and particularly, to a metal die casting machine having a unique safety bar mechanism for cushioning the stopping action of a movable platen for emergency or other reasons before the movable platen reaches the closed position of the dies.
In die casting machines, it has been the general practice to provide a safety bar which is connected to the movable platen and extends rearwardly to the rear or back platen. At the back platen, the safety bar has a plurality of transverse grooves spaced along the rear end of the bar which slides over the back platen as the movable platen is moved forwardly or rearwardly. A safety bar cylinder is mounted on the rear platen over the safety bar. The safety bar cylinder actuates a safety bar blade, which upon response to some emergency or other reasons for stopping the movable platen, is actuated by the safety bar cylinder into one of the grooves to immediately stop the movement of the movable platen.
In the operation of these safety bars, a problem has occurred because the inertial forces generated by movement of the movable platen and the sudden stopping thereof presents an energy dissipation problem, particularly on the larger die casting machines which, for example, might be in the order of 2,000 to 4,000 tons, such used to cast engine blocks or the like. The sudden stopping of the movable platen jars the entire machine creating havoc on all the components of the die casting machine requiring constant repair of the same.
In the smaller ton machines, the inertial forces generated by the movement of the movable platen and sudden stopping thereof can be counteracted by strengthening the machine pans and components. However, on greater sizes of die casting machines, the strengthening of the machine parts and components is nearly impossible and at least impractical. Therefore, there has been a long-felt need to provide some way in which this problem of the breaking down of the parts and components of die casting machines caused by the inertial forces generated by sudden stopping of the movable platen can be solved.